Forced air, fuel fired heater with scroll enclosed multiple annular heat transfer element



Aug. 14,-1951 G. B. HERBSTER 2,564,257

FORCED AIR, FUEL FIRED HEATER WITH SCROLL ENCLOSED Filed Nov. 21, 1947 MULTIPLE ANNULAR- HEAT TRANSFER ELEMENT 2 Sheets-Sheet l INVENTOR.

G'fO/Vf B. f/PBSTEIE 062a r fMJM/ ATTOE/YEYS Aug. 14, 1951 e. B. HERBSTER 2,564,257

FORCED AIR, FUEL FIRED HEATER WITH SCROLL ENCLOSED MULTIPLE ANNULAR HEAT TRANSFER ELEMENT Filed Nov. 21, 1947 2 Sheets-Sheet 2 IN V EN TOR. GEORG E B. HERBS TEE ATTOIE/VE x5.

Patented Aug. 14, 1951 FORCED AIR, FUEL FIRED HEATER WITH SCROLL ENCLOSED MULTIPLE ANNULAR HEAT TRANSFER ELEMENT George B. Herbster, Cleveland, Ohio, assignor, by mesne assignments, to 8600 Denison Company, Cleveland, Ohio, a corporation of Ohio Application November 21, 1947, Serial No. 787,455

4 Claims.

This invention relates to air conditioning devices and particularly to a gas fired heater of the forced air circulation type and is a continuation-in-part of my copending application Serial No. 663,506, filed April 19, 1946, which application has become abandoned.

' The heater or conditioning device therein fully described comprises a heat exchange means having :a central air inlet passage and a plurality of air outlet passages radiating therefrom and discharging at the periphery of the heat exchange means, and a blower or other means for circulating :air to be heated into the central passage and out through the radiating passages when it is discharged into the air at the periphery of the heater.

For space heaters and the like, the air can be discharged almost directly into the room or space to be heated. This arrangement is satisfactory inasmuch as only limited back pressure is built up in opposition to the discharge of the air. However, when used for a central heating plant in which the air must be accumulated in and discharged from a suitable plenum chamber through ducts and the like, or when used as a suspended heater from which it is desired to discharge the air more nearly downwardly from a level located above the floor, objectionableback pressure opposing the air flow results from the partial confinement of the air. This causes an unbalance between heat radiating surface and volume of air circulated which reduces the efliciency below practical limits.

One of the principal objects of the present invention is to provide an air conditioning device in which the air to be conditioned can be circulated more efiectively through the heat exchange means and discharged through a single outlet, or through a plenum chamber into a room, or through suitable ducts, or in a direction away from the ceiling in the case of a suspended heater.

In order to accomplish this result three important factors must be borne in mind. The first is the increase in the volume of air when it is heated. The second is the resistance to flow of the air through the radiating passages of the heat exchange means. The third is the relation between the volume of air to be heated and the area of heating surface. The manner in which these factors are taken advantage of will be apparent from the following description wherein reference is made to the drawings, in which:

Fig. 1 is a Vertical sectional view through a heater embodying the principles of the present invention;

Fig. 2 is a cross sectional view taken on the line 22 in Fig. 1;

Fig. 3 is a side elevation partly in section showing a modification of the casin of the heater illustrated in Figs. 1 and 2; and

Fig. 4 is a side elevation partly in section illustrating another modification of the heater illustrated in Figs. 1 and 2.

For the purposes of illustration, the invention is described in connection with gas fired heating apparatus of the forced air circulatin type, its use in connection with air cooling, and other air conditioning apparatus, being readily apparent from the illustrative example.

Referring to the drawings, the heat exchanger preferably comprises a plurality of disc-like substantially annular heat exchange heads I which have the same internal and external diameter as each other and each of which has a central passage 2. These heads are arranged in a row ,in coaxial relation to each other and are spaced apart axially. As a result, taken as a group, they define a, heat exchanger having a central passage coextensive axially with the heads and radially tending passages 3 between the heads and radiating from the central passage and openin at the outer periphery of the resultant heat exchanger.

As more fully described in my copending application, each of the heads i may be formed of two sheet metal stampings 4 which are corrugated so that when assembled, they provide in effect, a series of arcuate tubes which are segregated from each other and each of which has an integral combustion chamber portion 5 and an integral stack portion 6, the stack portion 6 being arranged at, and open at, the top and the chamber portion 5 being arranged at, and open at, the bottom.

Externally, the adjacent heads, due to the configuration of the corrugations, define radial passages 3 each of which, in radial cross section, is in the shape of a series of Venturi tubes arranged in end to end relation from the inner periphery of the heads outwardly, each Venturi. tube of each series having an entrance portion leading to a short throat and an expansion portion extending from the throat radially out wardl of the heads and being longer than the entrance portion of the next succeeding Venturi tube in the radially outward direction.

Since, as will later be described, the air delivered to the inlet of the passages 3 has a swirl- 3 ing motion, the air passes through the passages 3 with a swirlin motion so that along the spiral path of flow the passages 3 in effect ar elongated Venturi passages in the direction of flow of the air.

Since each heating head has its own stack portion and combustion chamber portion, the radial passages between the heads are unobstructed for their entire circumferential extent and radial extent and do not materially impede the swirling 2i motion.

The combustion chamber portion of each head I is preferably rectangular in horizontal section and of uniform size from its open bottom to its top. Each combustion chamber portion is wider and longer than its associated burner so that impingement of the burner flames on the inner upright Walls of the chambers or on the walls of the tubes is prevented.

Since the arcuate tubes of each head are segregated from each other and the combustion chamber portion of each head is unrestricted from bottom to top, there is an eiiicient distribution of the combustion products among the tubes of each head in proportion to their surface arrangement. Were each head a single radially wide tube, the combustion products would tend to concentrate near the inner periphery and cause an excessive heating at that location and reduced and inefficient heating near the outer periphery of the head.

Mounted within and preferably coaxial with the central passage through the row of head exchange heads I is a rotor of a centrifugal blower. In the form illustrated, the rotor indicated at l is preferably of the squirrel cage axial inlet radial discharge type adapted to receive air from the ends and discharge it generally radially. The

rotor l is mounted in bearings carried by suitable brackets 8 at the front and rear of the heating exchanger and the ends are left fully open for the free ingress of air axially of and Within the rotor. The rotor may be driven by any suitable means such, for example, as the pulley 9, belt 10, and electric motor H. ing media into the interior of the heat exchange heads I, a suitable burner I 2 is provided, the burner being arranged with head portions in which discharge directly into the combustion chambers 5, respectively.

At the bottom of the heads 8, they are connected with a top wall I3 of the burner compartment so that while heating media from the burner pass through the heads, none of the media is permitted to pass into the passages 3.

With the arrangement thu far described, a relatively high efilciency of air circulation can be obtained if the air is discharged from the periphery of the heating heads directly radially into the space to be heated.

When it is sought to enclose the heat exchanger in a casing and discharge it into a plenum chamber, or confined space, a back pressure builds up within the space with the result that the discharge of air is greatly reduced and the air tends In order to supply heatto swirl around the axis of the rotor in the passages 3 without discharging at the velocity and in the amount desired. In order to overcome this difficulty and provide for efficient discharge of the air, the entire head exchanger is enclosed in a coaxial casing having side Walls 14 arranged at opposite ends of the heat exchanger and a peripheral wall l5. The side walls 14 have central inlet passages 16 which are preferably coaxial with the rotor l and of such diameter as to lie at least inside the outer periphery of the blades of the rotor and preferably just at the inner periphery. Thus, air can be drawn into the rotor from both ends and discharged generally readily with a swirling motion through the passages 3. The peripheral wall 55 is spiral about the axis of the central passage of the heads l and at its portion of shortest radius is in contact With, or very close to, the outer periphery of the heads I. The radius of the peripheral wall 15 increases from this point in the direction of rotation of the rotor until it merges with a substantially tangential wall I! of the discharge duct of the casing, indicated at I 3. ihe discharge passage or duct l8 may lead into a distributing duct to which a large number of ducts leading to various rooms may be connected or, if desired, may discharge forwardly through a main discharge duct.

Thus, in effect, the heateror air conditioner comprises a centrifugal blower having an axial intake, radial discharge rotor and having a spiral casing with a substantially tangential discharge passage in which heat exchange elements are positioned between the rotor and the peripheral wall of the casing so that the air heated thereby can pass therethrough promptly and is afforded an ample passage which expands in the direction of air flow therethrough so as to eliminate back pressure. The air thus can discharge from the head at any point, almost immediately upon reaching the periphery of the heads, into the expansion chamber between the outer periphery of the heads and the peripheral wall. Since the spiral passage is expanding in the normal direction of swirl of the air, it accommodates a progressively increasing volume of air from its shortest radius portion to the outlet, thus allowing for expansion and progressive addition of air. As a result the air discharges from the radial passages throughout the whole circumferential extent of the heads I and flows freely out of the discharge duct 18 whereas, were the peripheral wall of constant diameter and against the heads, the air could not discharge from passages 3 except at the short circumferential extent of the discharge of the casing itself. In the latter case, most of the air would carry past the discharge passage and continue to swirl around through the pas sages 3, thus building up a back pressure and reducing the air flow too greatly.

Even with the spiral peripheral wall casing there is a tendency for some of the air to pass back into the radial passages at the trailing side of the duct is, due to the flow characteristics at the discharge of the casing. In order to eliminate this objection, a deflector or baffle 2| is provided on the peripheral wall at a point of minimum radius which is just at the trailing side of the discharge duct it in the direction of rotation. The bafile 2! extends into and partway across the discharge of the casing and lies against, or closely adjacent, the outer periphery of the exchanger. The free end of the bafile is turned upwardly and back in the direction of rotation, as indicated at 22 so as to eliminate eddy currents of the air in the duct l8 immediately in advance of the stack 6.

Thus the air can discharge. freelyfrom, the radial passages substantially throughout their circumferential extent and how freely alon h progressively expanding passage. Since the rotor is. of substantially the same diameter as the central passage so that no substantial free air space exists between the inner periphery of the heads and the rotor, no localized currents and axial air flow,. therebetween are created. The flow radially of the heads is relatively free, due to the Venturi shapes and the effect of elongation thereof when measured along the path of travel of the swirling air. Likewise, the Venturi effect provides a large heat exchange surface combined with intimate contact of the air and relatively free flow, thus maintaining a better ratio between radiating surface and volume of air.

In Fig. 3 there is shown a modification in which the only essential diiference from the structure of Figs. 1 and 2 resides in the fact that the peripheral wall of the casing is cylindrical and in contact with the outer periphery of the heads for a distance of about 90 about the rotor axis from a vertical line through the center of the stack, as indicated at 26 and is spiral therebeyond, as indicated at 21, in the direction of rotation, the same as the wall I5 of Figs. 1 and 2.

This modification has an advantage when the heating head is of limited radius or has relatively large radial passages because, under such conditions the air discharged radially from the rotor adjacent the stack and for a short distance therebeyond in the direction of rotor rotation would pass out of the head into the space between the head and peripheral wall after too short a period of contact with the heads to have become heated to as high a degree as desired. By employing the cylindrical portion 26, the air which would normally pass through the head too rapidly is confined and caused to effect a substantial circumferential travel before it passes out of contact with the head.

In Fig. 4 there is shown a modification of the invention for use as a space heater wherein it is desired to discharge the air generally radially of the heating head but in localized streams which may be directed downwardly toward the floor and upwardly toward the ceiling. In Fig. 4 the heating head, burner, and blower are the same as heretofore described but the casing indicated at 30 has an outer cylindrical wall 3! of constant diameter spaced from the outer periphery of the heating heads for its entire circumferential extent. The wall 3| has discharge openings 32 and 33 of substantial circumferential extent. Between the wall 3| and heating heads are peripheral baffle walls 34 and 35 each of which is coaxial with the rotor axis and substantially in contact with the outer periphery of the heating heads its leading end in the direction of rotor rotation and is spiral about the axis of the rotor from its leading to its trailing end. At its trailing end, each of the walls 34 and 35 terminates against the casing wall 3| adjacent to and immediately in advance of the associated one of the openings 32 and 33. If desired, blocking walls 36 and 31 may be provided between the spiral walls and the outer wall 3| as indicated, these being arranged just beyond the leading edges of the walls 34 and 35 respectively, in the direction of rotor rotation and extending from the outer periphery of the spiral walls to the wall 3|.

Thus, in eifect two separate spirally expanding passages forthe air, each having a spiral peripheral wall, are provided.

Having-thus described myinvention, I claim:

1. In a heater, a plurality of upright generally annular hollow heads arranged in a row in coaxial and spaced face to face relation to each other and providing a central passage with generally annular radial passages between adjacent heads'communicating with the central passage, each head being narrow in width endwise of the row relative to the radial dimension from its inner to its outer periphery and being in the form of an inlet portion extending from near to its inner periphery downwardly and opening downwardly, and an exhaust portion extending from near to its inner periphery upwardly and opening upwardly, said inlet and exhaust portions of each head being relatively narrow endwise of the row of heads and elongated in horizontal section in the plane of their head, and hollow portions extending about the central passage, one clockwise and one counterclockwise, from the inlet portion to the exhaust portion, each of the hollow portions being in communication at its lower end with the inlet portion and at its upper end with the exhaust portion, power driven blower means arranged at the central passage to cause air to enter the central passage and to force said air therefrom out through the radial passages, a fluid fuel burner means having portions respective to the heads and arranged to discharge combustible media separately directly upwardly in the inlet portions in spaced relation to the walls thereof to sustain combustion in the inlet portions, respectively, the inlet portion of each head being spaced, endwise of the row of heads, from the inlet portions of adjacent heads from the upper ends of the inlet portions downwardly at least near to the upper level of the burner means, and the exhaust portion of each head being spaced, endwise of the row of heads, from the exhaust portions of adjacent heads from the lower ends of the exhaust portions upwardly at least near to the level of the upper limits of the said hollow portions, whereby each of said radial passages is continuous circumferentially of the heads and the adjacent walls 01 adjacent inlet portions and adjacent walls of adjacent exhaust portions are swept by said air, a rigid casing comprising side walls and a generally spiral peripheral wall means, said casing enclosing the row of heads including the said exhaust portions from their lower ends upwardly near to the level of said upper limits of the hollow .portions and the inlet portions from their upper ends downwardly near to the level of the burner means, the said side walls being spaced respectively from the ends of the row of heads and at least one side wall having an opening in communication with said central passage, and said peripheral wall means extending about the periphery of the row of heads, whereby the heads, including the exhaust portions from their lower ends to the level of the upper limits of the hollow portions, and the inlet portions from their upper ends near to the level of the burner means, are swept by the air passing through the casing, and said casing having an outlet in its periphery at the large end of the spiral.

2. A heater according to claim 1 characterized in that said blower means includes a rotary blower radial discharge impeller which is open for receiving air axially at at least one end, and means rotatably supporting said impeller in and coaxial with said central passage.

3. A heater according to claim 1 characterized in that said peripheral wall means is closest to the outer periphery of the hollow portions near the exhaust portions and is of progressively greater radius therebeyond to its outlet, and said outlet is beyond the inlet portions of said heads in the direction of increasing radius of the peripheral wall means.

4. A heater according to claim 1 characterized in that each hollow portion includes means providing a plurality of spaced generally upwardly directed paths of flow for the media.

GEORGE B. HERBSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,877,905 Le Grand Sept. 20, 1932 1,884,898 Smith, Jr Oct. 25, 1932 FOREIGN PATENTS Number Country Date 185,531 Great Britain Sept. 14, 1922 307,161 Great Britain Mar. '7, 1929 530,879 France Oct. 11, 1921 

